Responding to the Threat of Skepticism: A Cartesian Microcosm

Since the advent of the skeptical project with Pyrrho of Elis, skeptical arguments have threatened the ability to make genuine knowledge claims.  Even the attitude of skepticism, that knowledge is impossible, threatens to dissuade one from taking up the search for knowledge in the beginning.  However, in refuting knowledge claims, skeptics such as Descartes place unnecessary requirements on our knowledge claims.  Descartes, in his Dream argument, requires us to eliminate any and all hypotheses that would result in our true beliefs being false.  This requirement makes responding to Descartes difficult.  As such, this paper will look at how we can respond to Descartes as well as what needs to be done to combat requirements such as those proposed by Descartes.

One of the most threatening skeptical claims is found in Descartes’ Dream argument.  Like Pyrrhonian arguments from perceptual relativity, the Dream argument calls into question the knowledge we obtain through our sense perceptions.  The structure of the Dream argument is very simple.  When one is dreaming, what one experiences in the dream is indistinguishable from what one experiences when they are awake.  In order to establish knowledge obtained through sense experience as genuine knowledge, we must be able to eliminate the possibility that we are dreaming.  If we were dreaming, beliefs that we might consider to be true could actually be false when compared to the actual reality.  Since experiences in the dream are indistinguishable from those when we are awake, we can’t adequately eliminate the possibility that what we sense is all taking place in a dream.  Therefore, we must conclude that sense experience cannot produce genuine knowledge. (Descartes 40-43)

The key idea here is Descartes’ notion that we must eliminate all possible contrary hypotheses in order to consider beliefs derived from sense experience as true and as candidates for knowledge claims.  The notion requires that we provide reasons for why we cannot be dreaming.  The problem, therefore, lies in that dream states produce the exact same phenomena that occur in our waking states.  Because of that fact, we cannot argue against Descartes on the grounds that there are certain things, such as yawning, which never seem to happen in our dreams.  Descartes would simply respond that we are unable to tell whether the moment in which we experience such phenomena is occurring in a dream state or a waking state.  We would be back to square one.  As such, our argument against Descartes must follow a different tact.

There are two things that we need to recognize before we respond to Descartes.  The first is that knowledge gained through sensory perception always purports to be knowledge about reality.  As such, this knowledge can only obtain in the reality in which the perceptions that lead to that knowledge occur.  Without a reality to experience there would be no beliefs, let alone knowledge.  The second item we need to consider is what it means to be dreaming and to be awake in this context.  To be awake is to experience reality as we seem to do in our everyday lives.  To put it simply, what we perceive to be happening is actually happening.  To be dreaming is to have the perceptions that we seem to have, but as a constant dream rather than actual reality.

Descartes, in the Dream argument, gives us a disjunctive statement: either we are dreaming or we are awake.  Descartes wants us to accept that being in a state of dreaming entails the possibility of our perceptions producing false beliefs.  However, this is not the case.  As we will see, dream states are just as likely to produce true beliefs as waking states.  Waking states it is clear, given that there are no illusions about what is reality, can give us true beliefs.  True beliefs, with justification, can be candidates for knowledge claims.  Therefore, if being in a waking state is true, knowledge is possible.

If we are in a dream state, it is also possible for us to have true beliefs and therefore knowledge.  This possibility rests upon recognizing that if we assume that we are dreaming then we must also assume that we are always dreaming.  The reason we must make this second assumption is that if we weren’t always dreaming, we would be able to distinguish between sleeping and waking through remembering either going to sleep or waking up.  Since we don’t have such memories, it is impossible for it to be the case that we fluctuate between dreaming and waking.  Thus, the dream state is effectively our reality, much like the waking state is our reality if we are not dreaming.

Descartes states that while we are in dream states we have beliefs, based on what we experience in the dream, that are true.  However, when compared to the actual reality that we would experience in a waking state, Descartes tells us that those beliefs are actually false.  Given the assumptions we have been forced to make above, this comparison is impossible to us as the perceiver because we have no access to waking states while we are in a dream state.  We can’t ascertain whether beliefs are true or false in relation to others.  We are left with the notion that the beliefs we have in the dream are true beliefs because we are in no position to experience any contrary belief.  Therefore, with the dream state as our reality and our sense perceptions while in the dream as the foundations for our beliefs, we are able to have true beliefs and candidates for knowledge claims.

We can then conclude that whether we are dreaming or awake, knowledge is possible.  Which one is objectively true is another matter, but given the limits of whichever reality we inhabit knowledge is possible in both dreaming and waking states.  This renders Descartes’ argument moot: identifying which state we’re in isn’t necessary to make knowledge claims as such claims are possible in both states.

Despite having responded to Descartes’ arguments, there is something we need to recognize about the way Descartes treats knowledge.  Descartes sets out the requirement that for something to be knowledge, we need to be able to successfully dismiss any contrary hypotheses that would make our beliefs false.  In this case, Descartes is preying on the lack of requirements for our knowledge claims outside of knowledge being justified true belief.  Traditionally, if a belief is true and we could justify our belief in it we would consider it knowledge.  Descartes’ requirement adds another layer to this account, making genuine knowledge even harder to come by.  In order to prevent requirements like the one proposed by Descartes, epistemologists must develop a more thorough definition of what is required for something to be knowledge.  Such a definition might simply prohibit notions like Descartes’ or it could further define what justification consists of.  The key point is to develop a working definition of knowledge that includes instances that we want to call knowledge and excludes instances that we don’t.

Now we must consider an objection to our response to Descartes.  We came to the conclusion above that we could not fluctuate between being in a dream state and being awake.  However, if we were to stipulate that such a transition is possible (along with the respective signs of transition) then we would be left with the problem of deciding which reality—either the dreaming or the waking—holds the objective truth.  We could assume that what we perceive while awake is objectively true, but we can’t be certain of that.  As such, Descartes’ notion of having to eliminate contrary hypotheses is back in play.  In order to determine which set of beliefs is objectively true, we must eliminate the other as a possibility.

This raises the question of why Descartes’ requirement is even needed.  Without Descartes’ requirement, we could safely assume that our experiences while awake are objectively true.  Given that we have stated above that a more thorough definition should be developed to combat requirements in this vein, we should now provide a reason why such requirements are unnecessary.  The argument here is rather simple.  Descartes’ requirement implies that there is some evidence that we can present that would clearly indicate which hypothesis is correct.  This is not the case in all situations. (Crumley 43)  For example, when choosing between dreaming and waking beliefs being objectively true, the only recourse we have is to argue that it simply makes more sense to believe that the beliefs we form when awake are objectively true.  Any evidence we present for the dream state would be derived from perceptions made while in the dream state and would thus be subject to possibly being objectively false.  The same applies for evidence presented for the waking state.  Thus, Descartes’ requirement is sometimes impossible to fulfill and because we want to preserve the possibility of knowledge, we must remove such impossible-to-meet requirements.

Since we have done away with Descartes’ requirement on those grounds, we are then free to assume that the true beliefs we gain in waking states are objectively true on the grounds that it seems more likely to us that our waking beliefs are true than our beliefs while dreaming.

While this singular look at Descartes’ Dream argument does not cover all skeptical arguments completely, some of the things expressed here carry over to other arguments as well.  The need to develop a thorough definition of what knowledge is should always be under consideration as well as examining whether the claims skeptics make are in the best interests of the greater epistemological project.  Also, it always pays to examine just what the arguments of skeptics entail.  They can often be caught in inconsistencies and spotting those inconsistencies is the first step to a successful refutation of skeptical claims.


Works Cited

Crumley, Jack S. An Introduction to Epistemology. Toronto: Broadview Press, 2009.

Descartes, Rene. “Meditations on First Philosophy.” Modern Philosophy: An Anthology of Primary Sources. Ed. Roger Ariew and Eric Watkins. 2nd Edition. Indianapolis: Hackett Publishing Company, 2009. 35-68.


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